生物柴油降凝剂的研究进展

生物柴油是绿色可再生能源,许多国家开始研究和使用生物柴油替代石化柴油。然而生物柴油低温流动性差,限制了其发展。从柴油降凝剂、生物柴油低温流动改进剂这两方面改善生物柴油低温流动性进行综述,并着重介绍作为生物柴油潜在添加剂的研究进展,最后对开发专门针对生物柴油降凝剂进行展望。     

生物柴油的组成对低温流动性的影响

生物柴油的化学组成是影响其低温流动性的重要因素。通过用气质联用仪和多功能低温试验器分别测定常见的6种生物的组成分布和浊点、倾点、冷滤点等低温流动性指标,用控制变量法研究生物柴油的组成和冷滤点的关系。结果表明,生物柴油中饱和脂肪酸甲酯的含量越高,饱和脂肪酸甲酯的脂肪酸碳链越长,生物柴油的低温流动性越差;不饱和脂肪酸甲酯的含量越高,脂肪酸甲酯的不饱和度越大,生物柴油的低温流动性越好;与饱和脂肪酸甲酯相比,不饱和脂肪酸甲酯对生物柴油低温流动性的影响可以忽略。     

生物柴油的组成对低温流动性的影响

生物柴油的化学组成是影响其低温流动性的重要因素。通过用气质联用仪和多功能低温试验器分别测定常见的6种生物的组成分布和浊点、倾点、冷滤点等低温流动性指标,用控制变量法研究生物柴油的组成和冷滤点的关系。结果表明,生物柴油中饱和脂肪酸甲酯的含量越高,饱和脂肪酸甲酯的脂肪酸碳链越长,生物柴油的低温流动性越差;不饱和脂肪酸甲酯的含量越高,脂肪酸甲酯的不饱和度越大,生物柴油的低温流动性越好;与饱和脂肪酸甲酯相比,不饱和脂肪酸甲酯对生物柴油低温流动性的影响可以忽略。     

生物柴油组分对低温流动性能影响的多元回归分析

为更好地了解生物柴油组分对其低温流动性的影响,探究组分与生物柴油低温流动性的关系,采用碱催化酯交换法制备生物柴油,对生物柴油进行低温流动性检测以及气相色谱-质谱联用仪(GC-MS)分析,同时利用多元回归的方法建立组分与低温流动性的关联式。结果表明,生物柴油之间低温流动性具有很大差异,菜籽油生物柴油的冷滤点和凝点温度最低,分别为-13和-10℃,棕榈油生物柴油的冷滤点和凝点温度最高分别为12和16℃,生物柴油的低温流动性主要由其组分的含量以及组分自身性质决定。通过GC-MS分析,生物柴油主要由5种脂肪酸甲酯构成,含量达90%以上;采用多元回归的方法,分析生物柴油组分对低温流动性影响,建立基于生物柴油主要组分(硬脂酸甲酯、棕榈酸甲酯、油酸甲酯、亚油酸甲酯、亚麻酸甲酯)的凝点、冷滤点、运动黏度的预测模型,相关系数均在0.95以上,可以很好地预测生物柴油的低温流动性。     

生物柴油低温流动性及其降凝剂的研究进展

生物柴油是典型的"绿色可再生能源".然而生物柴油的凝点一般在0℃时,其低温结晶和凝胶化限制了生物柴油在低温时的应用.生物柴油低温流动性能主要与生物柴油中的饱和脂肪酸甲酯的含量和分布有关,还与脂肪酸酯的支链程度有关.综述了改善生物柴油低温流动性的方法,降凝剂的作用机理及生物柴油降凝剂的研究、应用及发展前景.     

生物柴油高性能结晶抑制剂的研究

生物柴油是典型的"绿色能源",但相比石化柴油,低温流动性较差,这一性质严重限制了其在低温环境下的应用。添加低温流动改进剂是一种方便、快捷、有效的改善生物柴油低温流动性的方式。本文以四聚蓖麻油酸酯、马来酸酐、蓖麻油酸、环氧丙烷等为原料,合成了一种以长链树状脂肪酸酯为主要成分的化合物。在生物柴油中添加一定条件下制得的树状长链脂肪酸酯分子可有效地降低生物柴油的凝固点,从而对改进生物柴油低温流动性起到积极作用,可使生物柴油得到更广泛的推广和应用,对新能源的开发利用具有重要意义。     

掺混型生物柴油低温流动性研究进展

生物柴油的低温流动性能主要由生物柴油中饱和脂肪酸甲酯的组成、含量和支链程度决定,冷凝点一般为0 ℃左右,其低温结晶和凝胶化限制了生物柴油在天冷季节的使用.生物柴油作为柴油机燃料油一般与石化柴油按一定比例勾兑为掺混油使用.着重论述了国内外针对掺混型生物柴油低温降凝方面所做出的探索,并对前人提出的关于生物柴油降凝剂的研究作了简要评述.     

生物柴油低温流动性及改进方法研究进展

综述了生物柴油低温流动性评价指标、主要影响因素及改进方法等相关研究进展。介绍了生物柴油中的脂肪酸组成和分布、酯基结构及杂质组成与生物柴油低温流动性能的关系。论述了改善生物柴油低温流动性的几种主要方法:加入添加剂法、改变生物柴油结构、冬化处理等。其中加入添加剂法成本低,操作方便,将成为改进生物柴油低温流动性能的研究方向。     

生物柴油低温流动性能的研究

生物柴油是典型的绿色能源,主要成分是脂肪酸甲酯。生物柴油的低温流动性与饱和脂肪酸甲酯的含量及分布有关,还与脂肪酸酯支链程度有关。综述了改善生物柴油低温流动性的方法,分析了降凝剂对生物柴油的降凝机理以及今后的研究方向。     

支链醇生物柴油油酸异丙酯对生物柴油的降凝作用及机理研究

利用支链醇生物柴油油酸异丙酯作为降凝剂,对生物柴油的低温流动性进行了研究,实验结果表明,油酸异丙酯作为一种典型的支链醇生物柴油,对改善生物柴油的低温流动性具有明显的效果;同时将油酸异丙酯与柴油降凝剂复配,将其应用于地沟油制生物柴油,结果表明,油酸异丙酯与聚α-烯烃柴油降凝剂之间出现了明显的协同降凝作用,取得了较好的降凝效果。同时还研究了支链醇生物柴油降凝机理,并对协同降凝作用提出了观点。     

Partial hydrothermal oxidation of unsaturated high molecular weight carboxylic acids for enhancing the cold flow properties of biodiesel fuel

Biodiesel fuel has become more attractive recently because of its environmental benefits and the fact that it is a product made from renewable resources. However the less favorable cold flow properties or the low temperature operability of biodiesel fuel compared to conventional diesel is a major drawback limiting its use. The poor flow properties of biodiesel at cold temperatures are mainly due to biodiesel fuel being composed of long-chain fatty acids with an alcohol molecule attached. If the double bond of unsaturated fatty acids in these long-chain fatty acids could be ruptured selectively, then the cold flow properties of biodiesel fuel would be enhanced by reducing its viscosity.In this study, the selective hydrothermal oxidation of oleic acid, as a model compound of unsaturated high molecular weight carboxylic acids, was studied experimentally. The objective was to use this as a model to investigate whether the double bond of unsaturated fatty acids can be ruptured selectively by partial hydrothermal oxidation. Demonstration of this method could then be used to show the potential to improve the cold flow properties of biodiesel. Results showed that the amount of mono-carboxylic acids, aldehyde, di-carboxylic acids, and aldehyde-acids with a carbon number of 9 was significantly higher than other oxidative products. This suggests that the oxidative cleavage may principally occur at the double bond in hydrothermal conditions. The cloud and pour points for biodiesel fuel (B100) and B100 blend with a mixture of methyl esters or acetals were measured. These are the most important indicators for the cold flow properties of biodiesel fuel. The methyl esters or acetals used were made from the esterification of carboxylic acids or aldehydes by simulating the major oxidation products. These were obtained from the hydrothermal oxidation of oleic acid at different oxygen supply rates. Results showed that the cloud and pour points of the blend were significantly enhanced compared to those of B100.     

Effect of Metal-Based SiO2 Nanoparticles Blended Concentration on Performance,Combustion and Emission Characteristics of CRDI Diesel Engine Running on Mahua Methyl Ester Biodiesel

Silicon - Biodiesel has been renowned as potential and alternative fuel for years. In order to improve the quality of the conventional fossil fuels, biodiesel, and air pollution from combustion,...     

生物柴油低温流动改进剂复配研究

采用碱催化法制备菜籽油生物柴油和棕榈油生物柴油,对其主要品质指标进行分析;考察了添加不同的柴油低温流动改进剂及其复配物对生物柴油低温流动性能的影响。结果表明,柴油低温流动改进剂能够改善生物柴油低温流动性能;将其进行复配后,能表现出协同效应,取得更好的降滤效果,尤其能使饱和脂肪酸甲酯含量高的棕榈油生物柴油冷滤点降低8℃;不同生物柴油对柴油低温流动改进剂或其复配物感受性存在较大差异,不饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类较多、分布较广的菜籽油生物柴油对单一低温流动改进剂感受性好,而饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类分布较集中的棕榈油生物柴油对复配物感受性好。     

Performance and Emission Reduction Characteristics of Metal Based Sio2 Nanoparticle Additives Blended with Ternary Fuel (Diesel-MME-Pentanol) on CRDI Diesel Engine

Silicon - Biodiesel has been renowned as a potential and alternative fuel for years. To improve the quality of conventional fossil fuels, biodiesel, and air pollution from combustion, additives are...     

Methyl Esters (Biodiesel) from and Fatty Acid Profile of Gliricidia sepium Seed Oil

Increasing the supply of biodiesel by defining and developing additional feedstocks is important to overcome the still limited amounts available of this alternative fuel. In this connection, the methyl esters of the seed oil of Gliricidia sepium were synthesized and the significant fuel‐related properties were determined. The fatty acid profile was also determined with saturated fatty acids comprising slightly more than 35 %, 16.5 % palmitic, 14.5 % stearic, as well as lesser amounts of even longer‐chain fatty acids. Linoleic acid is the most prominent acid at about 49 %. Corresponding to the high content of saturated fatty acid methyl esters, cold flow is the most problematic property as shown by a high cloud point of slightly >20 °C. Otherwise, the properties of G. sepium methyl esters are acceptable for biodiesel use when comparing them to specifications in biodiesel standards but the problematic cold flow properties would need to be observed. The ¹H‐ and ¹³C‐NMR spectra of G. sepium methyl esters are reported.     

Dependence of biodiesel fuel properties on the structure of fatty acid alkyl esters

Biodiesel, defined as the mono-alkyl esters of vegetable oils or animal fats, is an “alternative” diesel fuel that is becoming accepted in a steadily growing number of countries around the world. Since the source of biodiesel varies with the location and other sources such as recycled oils are continuously gaining interest, it is important to possess data on how the various fatty acid profiles of the different sources can influence biodiesel fuel properties. The properties of the various individual fatty esters that comprise biodiesel determine the overall fuel properties of the biodiesel fuel. In turn, the properties of the various fatty esters are determined by the structural features of the fatty acid and the alcohol moieties that comprise a fatty ester. Structural features that influence the physical and fuel properties of a fatty ester molecule are chain length, degree of unsaturation, and branching of the chain. Important fuel properties of biodiesel that are influenced by the fatty acid profile and, in turn, by the structural features of the various fatty esters are cetane number and ultimately exhaust emissions, heat of combustion, cold flow, oxidative stability, viscosity, and lubricity.     

Cultivation of microalgae for biodiesel production: A review on upstream and downstream processing

Fluctuating market price of fossil fuel and overwhelming emission of greenhouse gases to the atmosphere have resulted in climate change and have been a global concern in this decade.Hence,biodiesel has become an alternative option to fossil diesel as it is renewable and environmentally friendly.Nevertheless,this alternative fuel that is usually derived from terrestrial oil crops will cause shortage in food supply and deforestation if mass production is realized.In recent years,cultivation of aquatic microorganism (particularly microalgae) to produce biodiesel is considered as a practical solution due to their high growth rate and ability to synthesize large quantity of lipid within their cell.However,the development of energy and cost-efficiency of microalgae cultivation system are the main issues in producing renewable microalgae biodiesel.Of late,wastewater or organic compost has been used as the cultivation medium as it can provide sufficient nutrients to sustain microalgae growth.Microalgae cultivation method and system are vitally important as these factors undoubtedly affect the final microalgae biomass and lipid yield.In this review,the cultivation system of microalgae,nutrients demanded for microalgae production,cell harvesting and drying,microalgae oil extraction,and utilization of microalgae biomass for biodiesel production are introduced and discussed.It is anticipated to convey clearer perspectives in upstream and downstream processes in microalgae-derived biodiesel production.     

Synthesis of biodiesel fuel from safflower oil using various reaction parameters

Biodiesel fuel is gaining more and more importance because of the depletion and uncontrollable prices of fossil fuel resources. The use of vegetable oil and their derivatives as alternatives for diesel fuel is the best answer and as old as Diesel Engine. Chemically biodiesel fuel is the mono alkyl esters of fatty acids derived from renewable feed stocks like vegetable oils and animal fats. Safflower oil contains 75-80% of linoleic acid; the presence of this unsaturated fatty acid is useful in alleviating low temperature properties like pour point, cloud point and cold filter plugging point. In this paper we studied the effect of various parameters such as temperature, molar ratio (oil to alcohol), and concentration of catalyst on synthesis of biodiesel fuel from safflower oil. The better suitable conditions of 1:6 molar ratio (oil to alcohol), 60 degrees C temperature and catalyst concentration of 2% (by wt. of oil) were determined. The finally obtained biodiesel fuel was analyzed for fatty acid composition by GLC and some other properties such as flash point, specific gravity and acid value were also determined. From the results it was clear that the produced biodiesel fuel was with in the recommended standards of biodiesel fuel with 96.8% yield.     

Various strategies for reducing Nox emissions of biodiesel fuel used in conventional diesel engines: A review

Energy demand, decreasing fossil fuel reserves, and health-related issues about pollutants have led researchers to search for renewable alternative fuels to either partially or fully replace fossil fuels. Among many alternative fuels, biodiesel became one of the most popular choices due to similar properties to that of conventional diesel. Biodiesel produces slightly lower brake thermal efficiency compared to that of conventional biodiesel, but has an advantage of reduced emissions of CO₂, CO, HC, and smoke. However, biodiesel shows higher NOx emission which, when used in increased biodiesel market, may become a serious problem. Various strategies were attempted by different researcher to reduce NOx emissions. In this paper, various strategies, adapted for reducing NOx emissions of biodiesel fuel used in diesel engines for automobile applications, are reviewed and discussed. The strategies are grouped into three major groups, namely combustion treatments, exhaust after-treatments, and fuel treatments. Among various strategies discussed, fuel treatments, such as low temperature combustion, mixing fuel additives and reformulating fuel composition, reduce NOx emission without compromising other emission and performance characteristics and they seem to be promising for future biodiesel fuel.